The end of life is getting complicated for terminal patients, their families and doctors.

Pressure to expand the pool of organ donors and improve the success of transplants has led physicians to redefine death and shorten times before organ harvest, researchers say.

Ethicists and theologians are struggling to keep up with medical advances.

“The church understands it is not a medical organization, and it looks to those in the health care field to guide those decisions,” said Edward Furton of the National Catholic Bioethics Center. “We hold that death is the separation of the soul of the body. We don’t claim to know exactly when that occurs,” he said.

The dead-donor rule says a donor must be dead before organs are removed for transplant.

Federal and Colorado death-defining statutes require the irreversible cessation of the heart or of brain function.

For 40 years, the irreversible cessation of brain function — a standard developed at Harvard Medical School — has been an accepted medical definition of death. Since the mid-1990s, pronouncement of death upon cardiac arrest, followed by removal of organs, also has become accepted medical practice.

And the number of organ transplants has doubled in the past 20 years, said Thomas Hooyman, an ethicist at Regis University, a Jesuit college.

Yet organ donation after cardiac death, while requiring simpler testing, has caused ongoing confusion and controversy, Hooyman said, in part because it often involves a decision to remove life-sustaining equipment, such as a ventilator.

Christian ethicist Dieumeme Noelliste of the Denver Seminary said death must precede steps for organ removal. “If there is any doubt the first action has taken place, then the second should not follow. We must ensure death is irreversible,” he said. “Both lives are sacred.”

Now, two high-profile doctors are calling for an end to the dead-donor rule. Robert Truog, a Harvard University professor of medical ethics, and Franklin Miller, a bioethicist with the National Institutes of Health, say the dead-donor rule has required “unsupportable revisions of the definition of death” and arguments over minutes.

The two doctors say the ethical requirement for organ donation in cases of devastating neurological injury is valid informed consent by families and other patient surrogates.

“It (informed consent) is ethically sound, optimally respects the desires of those who wish to donate organs and has the potential to maximize the number and quality of organs available to those in need,” Truog and Miller wrote in the Aug. 14 issue of the New England Journal of Medicine.

Truog and Miller wrote their opinion after Children’s Hospital followed its protocol of waiting less than two minutes after the hearts of two severely brain-damaged newborns stopped beating in April to remove those hearts and restart them in two other infants. The parents had authorized withdrawal of life support.

The Institute of Medicine, a think tank affiliated with the National Academy of Sciences, has advocated a five-minute wait after irreversible cessation of heart function.

Respected theologians had a comfort level with five minutes, Furton said. “The Catholic standard of erring on the side of life seems jeopardized,” he said. “You can’t take life, whatever good comes of it.”

While state education officials are sharing their proposals aimed at ending the teacher shortage in Colorado, the state’s largest teacher association says the overall plan lacks specifics and shortchanges traditional preparation programs.